The invention relates to the optoelectronic instrumentation engineering and data processing and measurement technology, and in particular it deals with cutting process control systems for CNC (computer numerical control) metal cutting machine tools.
2. Description of the Prior Art
Known in the art is an apparatus (SU, A, 772730) for controlling a machine-jig-tool-work system comprising a long feed drive, a comparator, and a negative feedback control channel, the apparatus being designed for correcting the relative position of the tool and workpiece and thickness of the removed layer.
However, the metal machining process is only controlled by indirect parameters of elastic deformation of individual members of the machine-jig-tool-work system without taking into account wear of the tool and kinematic errors in the servo drives of the carriage so that the accuracy of manufacture of parts is low. In addition, roughness of the workpiece surface is not controlled so that the machining process is not adaptive to the part quality.
The closest known prior art is an apparatus (SU, A, 1076859) for controlling the cutting process, comprising an optical transducer mounted on a metal cutting machine tool in the zone of a tool movement, the transducer comprising a laser, a narrow-field slit diaphragm mounted in the path of the laser beam, a reference half plane extending in the plane of the axis of rotation of the workpiece, a Fourier lens and an electronic interface unit comprising a series circuit including an image receiver and an analog-to-digital converter connected to the input of a CNC device.
The apparatus is designed for measuring the amount of dimensional wear of the cutting tool and for automatically compensating for such wear by effecting the cross feed of the tool by moving the carriage by the amount of the dimensional wear.
This apparatus does not, however, allow the kinematic error in servo drives of the carriage to be controlled; roughness of the part surface is not controlled, and the carriage position is only controlled in accordance with wear of the tool.